Miniaturization of electronic components such as consumer electronics and industrial equipment is a typical objective of design engineers and results in a more desirable and, typically, a lower cost product. To aid with the miniaturization of electronic components, it is a goal of semiconductor device manufacturers to offer packages having progressively thinner profiles and a smaller outlines.
One type of conventional semiconductor assembly, a thin small outline package (TSOP), comprises the use of a thinner lead frame and silicon die, bond wires having a decreased loop, and a thinner encapsulation layer surrounding the die in an attempt to form a smaller, thinner package. Another type of conventional semiconductor device assembly, depicted in FIGS. 1A and 1B, is referred to as a ball grid array or "BGA" device. BGA devices typically comprise a resin substrate 10 having one or more layers of traces therein (not depicted) which in effect provides a small printed circuit board (PCB). The device further comprises an array of pads on the bottom of the substrate to which solder balls 12 are attached. A noncircuit surface of a semiconductor die 14 is mounted to a side of the substrate opposite the balls 12. Bond pads 16 on the die 14 are wire bonded 18 to the traces 20 of the substrate 10, and then the die 14, the bond wires 18 and at least a portion of the traces 20 and the substrate 10 are encased in encapsulation material 22 such as plastic. The solder balls 12 on the BGA are contacted with pads on a PCB or socket (not depicted), then the solder 12 is reflowed to electrically couple the BGA with the PCB or socket. Ceramic equivalents to this design are also known in the art as are similar devices having leads instead of balls.
While decreasing the size and cost of components such as microprocessors, memory, and logic devices are goals of designers, the design described above has elements that are contrary to optimal component size. For example, to provide trace portions to allow wire bonding, the substrate must be larger than the die. The bond wires thereby extend laterally from the die to the traces on the substrate, and the device design results in the packaged BGA requiring additional lateral space beyond that required by the die alone. With regard to economy, the multi-layered substrates required by most BGA applications can be relatively expensive.
Further, the additional heat generated as device speeds increase contributes to component failure, and a package design which efficiently dissipates heat is an engineering design goal. A less costly BGA device having a smaller footprint and improved heat dissipation than previous devices would be desirable.